Technical Field of the Invention
This invention relates generally to wireless communication and more particularly to a method and apparatus for wirelessly monitoring repetitive bodily movements.
Description of Related Art
Laser (Light Amplification by Stimulated Emission of Radiation) systems are known for their use in wireless data gathering applications. For example, a laser-measuring tool, such as a laser rangefinder, uses a laser beam to determine the distance to and/or from an object. As another example, a laser is used for measurement based on the “time-of-flight” principle, which refers to sending a laser pulse in a narrow beam towards an object, measuring the time taken by the pulse to be reflected off the target, and calculating the distance based on the time. Other laser data gather applications include triangulation, interferometers, phase shift methods, and temperature measurements. Lasers can be used in three-dimensional (3D) object recognition, 3D modeling, and a wide variety of computer vision related fields.
Similarly, radio or microwave frequency signals are known for their use in wireless measurements. For example, radar systems are known object detection systems that use radio or microwaves to determine the range, velocity, or angle of objects. Radar systems use electromagnetic waves to measure distances. Common techniques for measuring distances using electromagnetic waves include time-of-flight, frequency modulation, and phased array method.
Radio and microwave frequency signals are further known for their use in motion detection. A tomographic motion detector uses a mesh system of radio frequency (RF) nodes. Changes in the baseline signal strength between nodes indicate a human presence or motion. This principle is typically implemented using signals in the 2.4 GHz range. A microwave based motion detector operates through the principle of Doppler radar. A continuous wave of microwave radiation is emitted (typically in the range of 915 MHz) and any phase shifts in the reflected microwave due to motion of an object are received as a heterodyne signal at low audio frequencies.
Airport security checkpoints and other security screening locations have implemented full body scanners to wirelessly detect concealed objects under a person's clothing. Whole body scanning is implemented through the use of backscatter X-ray, active millimeter wave, or passive millimeter wave technology. Backscatter X-ray scanners use weak X-rays to detect radiation that reflects from an object to form an image. Images are taken from both sides of the body to create a two-dimensional (2-D) image of the person and anything else on that person's body. Active millimeter wave scanners direct millimeter wave energy at the person and interpret the reflected energy. Because clothing and many other materials are translucent to extremely high frequency bands (EHF) such as the 24-30 GHz band emitted by millimeter-wave scanners, the wave energy reflected back from the body or other objects on the body is used to construct a 3D image, which can be displayed for analysis. In contrast, passive millimeter wave scanners create images using ambient radiation and radiation emitted from the human body or objects.
Bluetooth is a known wireless technology for exchanging data over short distances from fixed and/or mobile devices and building personal area networks (PANs). Bluetooth technology uses short wavelength, ultra high frequency (UHF) radio waves in the industrial, scientific, and medical (ISM) radio band from 2.4 to 2.48 GHz to establish wireless connections between devices.
Currently, “wireless” heart rate monitors include a sensor that makes contact with the body (e.g., a sensor attached to the wrist, across the chest, etc.) that wirelessly communicates with another device (e.g., a smart phone, watch, etc.). As such, wireless heart rate monitors require contact with the human body to sense the appropriate data.